Preheat the oven to 200˚C, gas mark 6. Toss the squash with ½ tbsp oil, season and spread over a large, parchment-lined roasting tin. Roast for 15 minutes. In a bowl, toss the gnocchi with ½ tbsp oil and the sage, then stir into the tin with the squash. Roast for another 10-12 minutes, until the gnocchi is piping hot.
Meanwhile, heat the remaining ½ tbsp oil in a large frying pan over a medium-high heat. Fry the onion with some seasoning for 3-4 minutes, until softened and turning golden. Add the cabbage and 2 tbsp water; fry for another 3-4 minutes until tender.
Lower the heat under the cabbage and stir in the squash, gnocchi and sage. Stir through the crème fraîche, most of the cheese and another 2 tbsp water, tossing together until coated. Serve immediately, with the remaining cheese sprinkled over.
